1. Field of the Invention
This invention relates to electrical connectors in general, and, in particular, to a cable connector which permits an electrical cable having multiple conductors to be removably connected to electrical circuits on a printed circuit board or back panel.
2. Summary of the Prior Art
Electronic circuits for many applications including, for example, for telecommunications applications, are becoming increasingly faster and more complex with a need to accommodate many electrical circuits and components on printed circuit boards or back panels. It is frequently necessary in complex systems to interconnect circuits contained on back panels to circuits in other locations, for example by using multi-wire electrical cabling. As electronic circuits increasingly become more complex and faster in operation, their sensitivity to radio frequency interference and other electromagnetic radiation increases. Consequently, there is a need to protect the interconnections between back panels and other components which are connected by cable from stray electromagnetic interference and other forms of interferences (sometimes referred to as "EMI-RFI" interference). Electrical cables connecting electronic circuits in other locations to back panels are frequently isolated from cross-talk by encasing the signal conductors in a conductive shield. Since it is advantageous to connect a multi-wire electrical cable to a back panel with a connector which can be readily disconnected without breaking solder joints, it would also be advantageous to have shielding on the electrical connector to avoid introducing cross-talk into the signal carrying conductors through the unshielded connector. This arrangement would be particularly useful where a cable connector is connected to signal carrying pins which are installed in a pin field on a back panel, since failure to properly insulate the pin field from stray electromagnetic signals may result in the pins acting as antennae with the attendant degradation of signals being transmitted between the cable and circuits on the back panel. In addition, it would also be advantageous to have an electrical connector which provides grounding between the conductive surfaces on the cable-end of the connector and ground planes contained on the back panel.
Use of metal shielding to shield connectors from stray electromagnetic radiation is known in the prior art. However, metal shielding is bulky and is frequently difficult to accommodate in high density connectors, that is, in connectors having a substantial number of contacts in a confined space. In addition to having the contacts in a connector electrically isolated from stray electromagnetic radiation, it would be also advantageous to shield adjacent pins and pin contacts from both stray electromagnetic radiation and cross-talk produced by the transmission of signals from one wire in a multi-wire cable into adjacent contacts through the electrical connector.
One form of cable connector for use in effecting contact between multi-wire cables and circuits on printed circuit boards is manufactured by Harting Electronik of Germany and is sold under the trademark "Har-Pak". While the system is modular and permits making high density contacts between cables and circuits on printed circuit boards, there is still a need for a more flexible approach to making interconnections between multi-wire cables and a printed circuit board, including a need for achieving EMI-RFI shielding on both the male and female portions of the connector system.
While there are a variety of electrical connectors available for effecting connections between signal carrying wires in a multi-wire cable and electrical circuits contained on a printed circuit board or back panel, the combination of an electrical connector which includes closely spaced contacts for connecting circuits in a multi-wire cable to a pin field on a back panel and which also provides EMI/RFI shielding to isolate the circuits from stray electromagnetic radiation and which also includes a keying capability to insure that the cable-end of the connector makes electrical contact with the proper pins in a pin field is not known. Furthermore, it would advantageous to have an electrical connector for making connections between a multi-wire cable and a pin field on a back panel which can be configured to permit the number of contacts in the cable-portion of the connector to be designed to accommodate a specific number of pins in a pin field on a back panel. The connector disclosed herein not only permits the quick connection of multiple wires in a cable to circuits on a printed circuit board but also insures that isolation from stray electromagnetic radiation is achieved between the cable-end of the connector and the printed circuits contained on the back panel.